Educator Resources

While excavating just outside Yellowstone National Park, a team led by paleontologist Jonathan Bloch of the Florida Museum of Natural History discovered two remarkably preserved fossils. The 56-million-year-old specimens belong to a group of archaic mammals, the plesiadapiforms (please-ee-ah-DAPE-i-forms). These small mammals were as small as mice, ate fruit, and lived in trees. The new fossils offered compelling evidence that the plesiadapiforms are more closely related to modern primates than to flying colugos, which had previously been proposed. Instead of having webbed hands or gliding flaps like colugos, plesiadapiform fossils showed hands that could grasp and manipulate food—a defining trait of primates.